Summary : Balancing chemical reaction
• Once chemical formula of specie is determine, do not change
• Assign coefficient of 1, to most complicated molecule
• Balance Homogeneous atomic molecules last i.e., H2,
• Balance cation/anion as a single unit (i.e., if occurs in
reactant and product unchanged)
• Convert fractions to integers.
Try the following as an exercise.
Example # 3:
Balancing a double displacement (metathesis)
Consider the reaction:
Mg(NO3)2 + KOH Products
What are the products formed and how can the equation be balanced
3 ways of writing the chemical
reaction for a double displacement reaction:
a) Molecular equation; Equation
showing overall reaction stoichiometry, but not the form of reactant
or product in solution. (The forms are implies by the phase-subscript).
b) Complete ionic equation;
Equation showing ions that are strong electrolyte.
c) Net ionic equation; Equation
showing only substances undergoing chemical changes.
a) Molecular equation:
+ 2KOH(aq) 2KNO3(aq) + Mg(OH)2
b) Complete ionic equation:
+ 2 NO3- (aq) + 2 K+(aq) + 2 OH-(aq) 2 K+ (aq) + 2 NO3-
(aq) + Mg(OH)2 (s)
c) Net ionic equation:
Mg2+(aq) + 2 OH-(aq)
#4 . Balancing a neutralization reaction ( a form of
Acids - provides
- provides OH-
Water is produce and a salt (ionic compound)
salt : (cation - anion)
acid in water; at a
molecular level. - (Aqueous chemistry)
Try the folloinw as exercise.
oxide and water forms sodium hydroxide
Sulfide & molecular oxygen yields ferric(III) oxide & sulfur
#7 C4 H10 (g)
+ O2 (g) H2O(g)
+ CO2 (g) (combustion)
In a combustion reaction, water, CO2
and energy are always produced.
#8 H2SO4 (aq) + Ca(OH)2 (aq) H2O(l) + CaSO4 (s)